Base metal pigment, aqueous base metal pigment dispersion liquid, and aqueous ink composition

Abstract

Disclosed herein is a base metal pigment, which is used for an aqueous ink composition containing water as a part of a solvent, in which the base metal pigment is surface-treated with a fluorine-based compound, and has a zeta potential of greater than or equal to −50 mV and less than or equal to −15 mV, as measured by an ultrasonic zeta potential measurement device, in a pH range of greater than or equal to 5 and less than or equal to 10.

Description

BACKGROUND[0001]1. Technical Field[0002]The present invention relates to a base metal pigment having excellent water resistance and dispersion stability in an aqueous medium, an aqueous base metal pigment dispersion liquid containing the base metal pigment, and an aqueous ink composition containing the base metal pigment.[0003]2. Related Art[0004]In the related art, as methods of forming a coating film having metallic luster on a printed matter, a foil press printing method using a printing ink or metal foil, in which gold powder or silver powder made of brass, aluminum microparticles, or the like is used in a pigment, a thermal transfer printing method using a metal foil, and the like have been used. However, these methods are problematic in that it is difficult to form a fine pattern or to apply these methods to a curved surface. Particularly, the foil press printing method is problematic in that on-demand properties are low, the application thereof to multi-product production is ...

AI Technical Summary

Benefits of technology

[0071]The surface treatment of the mother particle using the fluorine-based compound may be performed by directly treating the surface of the mother particle with the fluorine-based compound, but may also be performed by surface-treating the mother particle pretreated with acid or base using the fluorine-based compound. In this case, the chemical modification can be more definitely performed on the surface of the mother particle by the fluorine-based compound, and the above-mentioned effects of the invention can be more effectively realized. In addition, even when an oxide film is formed on the surface of particles to be the mother particles before the surface treatment of the mother particle using the fluorine-based compound, this oxide film can be removed, and the surface treatment of the mother particle using the fluorine-based compound can be performed in the state where the oxide film is removed, and thus the metallic luster of the manufactured base metal pigment can become more excellent. Examples of the acid used herein may include protonic acids, such as hydrochloric acid, sulfuric acid, phosphoric acid, nitric acid, boric acid, acetic acid, carbonic acid, formic acid, benzoic acid, chlorous acid, hypochlorous acid, sulfurous acid, hyposulfurous acid, nitrous acid, hyponitrous acid, phosphorous acid, and hypophosphorous acid. Meanwhile, Examples of the base used herein may include sodium hydroxide, potassium hydroxide, and calcium hydroxide.

[0072]Subsequently, solvent substitution is performed. Specifically, a dispersion liquid, in which a base metal pigment is dispersed in a non-aqueous medium, is centrifugally separated to remove a supernatant liquid, the following aqueous medium previously prepared by mixing is added to this dispersion liquid in an adequate amount, and then the resulting dispersion liquid is irradiated with ultrasonic waves, thereby dispersing the base metal pigment in the aqueous medium. By the above process, the base metal pigment (aqueous base metal pigment dispersion liquid) according to the present embodiment is obtained. In addition, the base metal pigment obtained in this way is also preferably heated. It is predicted that the fluorine-based compound physically adsorbed on the surface of the mother particles is dehydrated by heating to form covalent bonds, and thus the mother particle and the fluorine-based compound are more strongly bonded to each other, thereby more effectively exhibiting the above-mentioned effects of the invention. The heating temperature is preferably higher than or equal to 50° C., and more preferably higher than or equal to 60° C. The heating time is preferably 1 day to 10 days. Further, it is preferred that the heat-treated base metal pigment be washed with an aqueous medium. Therefore, the fluorine-based compound, which is physically adsorbed on the surface of the base metal pigment so as to be easily detached therefrom, can be removed, and the unnecessary fluorine-based compound can be removed from the aqueous medium, thereby further improving the dispersion stability of the base metal pigment in the aqueous medium. In terms of increasing detergency, a solvent (for example, 2-methyl-2,4-pentanediol) having an ability of dissolving the fluorine-based compound or the following fluorine-based surfactant may be added to the aqueous medium used in the washing.

[0073]The above-mentioned aqueous medium may be a medium containing water as a main component, and may also be added with an organic solvent, a surfactant, a tertiary amine, a pH adjuster, or the like. The content ratio of water in the aqueous medium is preferably more than or equal to 20 mass %, more preferably more than or equal to 30 mass %, and particularly preferably more than or equal to 45 mass %.

[0074]Preferably, the organic solvent that can be added to the aqueous medium is a polar organic solvent, in terms of compatibility with water. Examples of the polar organic solvent include alcohols (methyl alcohol, ethyl alcohol, propyl alcohol, butyl alcohol, isopropyl alcohol, fluorinated alcohol, and the like); ketones (acetone, methyl ethyl ketone, cyclohexanone, and the like); carboxylic acid esters (methyl acetate, ethyl acetate, propyl acetate, butyl acetate, methyl propionate, ethyl propionate, and the like); ethers (diethyl ether, dipropyl ether, tetrahydrofuran, dioxane, and the like); polyhydric alcohols (ethylene glycol, diethylene glycol, triethylene glycol, polyethylene glycol, polypropylene glycol, propylene glycol, butylene glycol, 1,2,6-hexanetriol, thioglycol, hexylene glycol, 1,2-hexanediol, glycerin, trimethylol ethane, trimethylol propane, and the like); lactams (2-pyrrolidone, and the like); and glycol ether solvents (alkylene glycol monoethers such as triethylene glycol monobutyl ether, alkylene glycol diethers such as diethylene glycol diethyl ether, and the like). The content ratio of the organic solvent in the aqueous medium is preferably less than or equal to 60 mass %, and more preferably 35 mass % to 55 mass %. When the content ratio of the organic solvent is within the above range, the water resistance of the base metal pigment is improved, and simultaneously the metallic luster thereof becomes better.

[0075]Preferably, the surfactant that can be added to the aqueous medium is a fluorine-based surfactant and / or a silicone-based surfactant. The content ratio of the surfactant in the aqueous medium is preferably less than or equal to 3 mass %, more preferably 0.01 mass % to 2 mass %, and particularly preferably 0.1 mass % to 1 mass %. When the content ratio of the surfactant is within the above range, the water resistance of the base metal pigment tends to be more improved. In addition, at the time of recording a metallic luster image, the surfactant functions as a slip agent, and is effective at improving the friction resistance of an image.

[0076]Examples of the fluorine-based surfactant include Megafac F-430, Megafac F-444, Megafac F-472SF, Megafac F-475, Megafac F-477, Megafac F-552, Megafac F-553, Megafac F-554, Megafac F-555, Megafac F-556, Megafac F-558, Megafac R-94, Megafac RS-75, and Megafac RS-72-K (all are trade names, manufactured by DIC Corporation); EFTOP EF-351, EFTOP EF-352, EFTOP EF-601, EFTOP EF-801, and EFTOP EF-802 (all are trade names, manufactured by Mitsubishi Materials Corporation); FTERGENT 222F, FTERGENT 251 and FTX-218 (all are trade names, manufactured by Neos Co., Ltd.); and Surflon SC-101 and Surflon KH-40 (all are trade names, manufactured by AGC Seimi Chemical Co., Ltd.).

Problems solved by technology

However, these methods are problematic in that it is difficult to form a fine pattern or to apply these methods to a curved surface.

Particularly, the foil press printing method is problematic in that on-demand properties are low, the application thereof to multi-product production is difficult, and the printing of a gradational metal tone is impossible.

However, when an aluminum pigment, as a kind of base metal pigment, is dispersed in water, alumina is formed together with the generation of hydrogen gas by the reaction with water to cause a whitening phenomenon.

However, the aluminum pigment disclosed in each of the above Japanese Patent No. 4358897, Japanese Patent No. 3869503, Japanese Patent No. 2759198, and JP-A-2006-199920 is problematic in that water resistance is insufficient, and in that surface state is changed by the oxidation proceeding over time in an aqueous medium, and thus dispersion stability deteriorates.

In addition, when the surface of aluminum is coated, there is a problem in that the oxidation of aluminum proceeds during the surface coating, and thus agglomeration easily occurs together with the deterioration of luster.

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